Several years after being detected here, the emerald ash borer (Agrilus planipennis, EAB) continues to munch on a potential feast of more than 150 million ash (Fraxinus) trees in Vermont. That's 5 to 7 percent of the state's trees on average or about 1 in 12 trees, although in some areas, such as the Champlain Islands, the number is more like 40 percent.
Losing this many trees would clearly have a significant impact, but there's still time to plan proactively and identify ashes.
UVM Extension Forest Pest Education Coordinator Ginger Nickerson says it's important for municipalities to know how many ash trees are on public land so they can determine plans to manage them.
“Ash trees become very brittle when they die and break in unpredictable ways, so it is important for public safety to remove potentially hazardous trees while they are still alive,” Nickerson says.
Vermont's Urban and Community Forestry Program (UCF) has resources to help towns inventory public trees. Dummerston and Guilford are two towns in Windham County that have used UCF's Rural Roadside Ash Inventory Tool to inventory ash trees along municipal roads.
Dummerston inventoried 534 ash trees; Guilford inventoried 2,744.
The invasive EAB is native to southeast Asia and responsible for killing millions of ash trees throughout the U.S., known to be established in at least 32 states and three Canadian provinces. EAB is responsible for widespread decline and death of hundreds of millions of ash trees in North America.
The Vermont Department of Forests, Parks & Recreation (FPR) and the Vermont Agency of Agriculture, Foods & Markets (AFM) has confirmed the destructive insect's presence here.
Nickerson says the first find was an adult beetle - as opposed to an infested tree - in Londonderry the fall of 2019.
“This summer, adult beetles were caught in traps in Wilmington and Vernon during the mid-season check in July,” she says. “We are still processing the trap results from the end of the flight season and will have those in October.”
The adult beetles are small and spend most of their time in tree canopies.
“While it is not impossible, it is unlikely for people to see the adult beetle,” Nickerson says. “They are more likely to see infested ash trees.”
Trees with EAB may show a thinning canopy with dead branches, or a lot of “epicormic sprouts” or new side branches coming off of the main trunk.
But the most definitive sign is if the tree has a lot of woodpecker activity - the outer bark of the ash will flake off as the woodpeckers are going after the beetle larvae, causing the tree to have “blond patches.”
Sometimes, you can even see the holes left by the woodpeckers' beaks. If people see an ash tree they think is infested, they should take photographs of the tree and symptoms and submit them using the ReportIt links on the VTinvasives.org website, where photographs help identify symptoms.
How bad is it?
Nickerson says it can take three to five years from when an ash tree is first infested to when it starts showing symptoms and/or dies.
“What that means is that although EAB was first discovered in Vermont in February 2018, the pest had probably been present in the state for at least a couple of years prior,” she says.
The Agency of Natural Resources maintains a map of the current infestations which is updated whenever a new infestation is confirmed. You can find it on the emerald ash borer pages at VTinvasives.org.
Nickerson explains that each yellow circle on the map represents a 10-mile radius around a known EAB infestation. The relative severity of infestation is represented by the colors in the circles.
A yellow infested area indicates a less severe infestation, while an orange or red area has a more intense infestation with more trees affected. While EAB symptoms may not yet be obvious everywhere within a yellow circle, it is likely that EAB is present in much of this area or will be soon.
“The heaviest infestations are in the places where we first started seeing infested trees, near the intersection of Caledonia, Orange and Washington counties, and in the Champlain Islands,” Nickerson says. “There is a heavy infestation in the town of Orange that has spread north to Plainfield. The other heavy infestation started in South Hero and is spreading through the islands.”
She points out that since the pest does not recognize borders, it is important to also be aware of confirmed infestations in other states.
For example, New Hampshire has confirmed infestations in Langdon, Hinsdale, and Winchester and the 10-mile “potential expansion area” from those infestations - areas where one expects the pest to be spreading, if it is not there already - come into sections of Windham County.
Several towns in Massachusetts that border Windham County have also confirmed infestations.
“Although right now we only have these two 'hot spots' in central Vermont and the islands, eventually the pest will spread throughout the state,” says Nickerson.
“The good news is that it will be a number of years before we start seeing ash trees dying in significant numbers across the state,” she continues.
“People in towns with new EAB finds still have time to plan and take proactive steps with their ash trees,” Nickerson says. “This means municipalities should inventory the public ash trees so that they know how many ash trees they have to manage, and come up with a plan for how they will manage them.”
What homeowners can do now
Vermont's UCF Technical Assistance Coordinator Joanne Garton is available to help train people to conduct ash inventories. Sample municipal EAB management plans as well as many other resources for municipalities and volunteers are available at VTcommunityforestry.org.
Private landowners have time to consult with a forester about how they want to manage the ash on their woodlots and forested lands, and homeowners have time to talk with arborists about whether to treat ash in their yards.
“But if you are within one of the yellow circles, you should take these steps sooner rather than later,” says Nickerson.
“While we continue to find new areas of infestation, the majority of our forests currently have healthy populations of ash that we should protect as long as possible,” she says. “This means it is still very important to slow the spread of the pest by not moving ash firewood from an infested area to an uninfested area - moving firewood is one of the primary ways pests and diseases are spread to new locations.”
Look for more recommendations at “Slow the Spread” for different industries and activities at VTinvasives.org.
“Unfortunately, one of the things we have learned from states in the midwest that have been dealing with EAB since the early 2000s is that it is not possible to eradicate EAB,” Nickerson says.
“It is not an insect that we can spray for and get rid of,” she says. “Now that it is here, it is here to stay.”
If homeowners think they have infested ash trees, the first step is to confirm that the tree is an ash.
A property owner can take photographs of the symptoms and submit them using the ReportIt links at VTinvasives.org, and Nickerson's team will follow up.
Professional arborists can also be retained to look at and identify a tree.
Once the tree is confirmed to be an ash and infested, a property owner can work with a certified professional arborist and pesticide applicator to determine if it is possible to save the tree or if it should be removed and replaced with another species.
Overall, Nickerson has two recommendations: “Don't move firewood, and don't panic.”
“While we continue to find new areas of infestation, most of our forests currently support overwhelmingly healthy populations of ash that we should protect as long as possible,” she says. “Bearing that in mind, we urge Vermonters to continue to follow the Slow the Spread recommendations.”